Math & Everyday
Percentage Calculator
Percent of a value, share of total, or change over time.
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CalcoTools · Percentage Calculator · generated 8/23/2026, 12:24:54 PM
About the Percentage Calculator
Handles the three percentage questions people ask most often — finding a percentage of a number, expressing one number as a percentage of another, and calculating percentage change between two values.
How to use it
- For X% of Y: enter the Percent and the value it's Of.
- For A is what % of B: enter both values.
- For percent change: enter a From and To value.
- Read each section's result in its own readout.
Formula
X% of Y = (X ÷ 100) × Y
Percentage change = ((New − Old) ÷ Old) × 100
Worked example
A $340 jacket marked 25% off: 25% of 340 = 85, so the discount is $85 and the sale price is $255.
Recommendations
- • When comparing prices, percent change is usually more useful than the raw dollar difference.
- • For compounding discounts, like a coupon on top of a sale, apply each percentage in sequence rather than adding them together.
- • A negative percent change simply means a decrease — no need to second-guess the sign.
Frequently asked questions
A change from 40% to 50% is a 10 percentage-point increase, but a 25% relative increase (10 ÷ 40). This tool's percent-change mode calculates the relative figure.